Sewer & Stormwater Services

Rainwater Management

A storm drain with natural debris and water

When it rains, stormwater washes over streets, roofs, lawns, and parking lots — picking up oil, sediment, bacteria, grease, and chemicals that can pollute our streams and the Tualatin River.

Clean Water Services and city staff are responsible for the system of flow of stormwater, or runoff, from one location to another, known as stormwater conveyance. To maintain this, CWS provides the following services:

  • Maintenance of the public stormwater conveyance system, including 529 miles of the 1,565 miles of storm sewers and pipelines, open ditches, stormwater detention ponds, and water quality facilities. 
  • Sweeping curbed public streets monthly and cleaning storm drains and catch basins.
  • 24-hour emergency response to flooding and water pollution complaints.
  • Water quality investigation and spill response.
  • Monitoring of water quality in the Tualatin River and its tributaries.
  • Development of design and construction standards.
  • Implementation and enforcement of construction site erosion control regulations.
  • Protection of Vegetated Corridors (buffer zones) between new development and creeks and wetlands.
  • Construction of regional water quality, stream enhancement, and flood management projects.
  • Watershed planning for the long-term health of our urban streams.
  • Public education, outreach, and partnerships for pollution prevention and watershed health.
  • Private Water Quality Facility Management Program.
  • Clean Water Services does not maintain private drainage systems or have the authority to intervene in private lot-to-lot (PDF) drainage disputes.
  • Floodplains are regulated by many State and Federal agencies, and floodplain information is available through the Washington County Flood Information website.

What are surface waters?

Surface waters consist of streams, wetlands, rivers, and springs. Surface waters can be impacted by activities in the watershed. Improving their health involves addressing water flows (high and low), vegetation conditions, habitats, invasive species, human encroachment, and sources of pollution. Activities such as tree planting, enhancement, culvert repairs, stormwater outfall improvements, and flow restoration are prioritized through watershed planning conducted by Clean Water Services. Refinement of regulations, educational opportunities, incentives, and other program activities that improve surface waters are an ongoing aspect of the Surface Water Management (SWM) Program. Clean Water Services, our 12 partner cities, Washington County, Friends groups, and other watershed partners all pitch in to help improve our water resources.

What can you do?

Protecting our neighborhood streams, wetlands, and the Tualatin River begins at home. We all play a role in maintaining a healthy environment and a livable community.

Clean Water Services is working hard to protect water quality in our streams, but we need your help. Here are some tips to help you protect local creeks and the Tualatin River.

  • Mark storm drains in your neighborhood with the “No Dumping, Drains to River” message. 
  • Properly dispose of or recycle motor oil, antifreeze, paint, solvents, and other toxic materials.
  • Keep leaves, grass clippings, dirt, and litter out of storm drains, ditches, creeks, ponds, and wetlands.
  • Clean up after your pets to avoid stream contamination from bacteria and parasitic organisms.
  • Use non-toxic alternatives or the least toxic pesticides and herbicides. Learn more about herbicide use in our Herbicide Fact Sheet (PDF).
  • Do not over-fertilize lawns and your landscape.
  • Disconnect roof drain downspouts when applying moss control products on roof. For more information, please download our Safe Roof Moss Control Fact Sheet (PDF).
  • Don’t allow soaps and detergents from car washing to flow down the street or into catch basins.
  • Plant native groundcover and shrubs to cover bare earth and prevent erosion.
  • Report flooding or other serious problems to Clean Water Services.